Composite armor materials provide superior protection against impacting projectile threats by using a combination of light-weight and high-strength materials. It is essential that the projectiles are defeated and their energy absorbed or dissipated in a non-lethal manner. For a composite of specific areal density (weight/unit area), resourceful configurations are needed so that the ballistic properties are optimized to the greatest extent. For transparent armor applications it is required that the requisite protection is provided without compromising the visibility. It is also required that protective structures maintain a significant level of their structural integrity after impact so that they provide protection and/or retain significant visibility through successive hits. Armor composites are fabricated using a wide spectrum of materials (metals, ceramics, polymers, organic materials) in various structural forms (monoliths, foams, fabrics, fibers, foils, meshes etc.) A combination of two or more of the above materials can be used depending upon target application and threat. The prior art in composite armor design is well documented with various examples which typically incorporate different materials in laminated structures. Transparent armor systems are comprised of constituent transparent materials such as polymers (poly (methyl methacrylate), polycarbonate, polyurethane, etc.), ceramics (magnesium oxide, spinel, sapphire, aluminum oxynitride etc.) or glass (soda lime, pyrex, tempered glass). Though laminates improve the mechanical properties considerably and are easy to manufacture, they are prone to poor modes of failure such as delamination. Also, cracks are often induced in the more brittle and stiffer components and can propagate extensively across the entire armor plate and ultimately limit structural integrity after a hit.
Some prior art designs explore non planar pellets/components in the armor composite to help defeat/deflect/disorient the projectile. For example, U.S. Pat. No. 3,563,836 discloses using a closed packed distribution of conical discs to help improve the flexibility and increase shear force transfer. There has been a lack of designs, however, that optimize the protection by leveraging the geometrical arrangement of various components and maximizing their synergy depending on the threat conditions.
There is a need, therefore, for more effective and efficient materials and articles for use in projectile impact protection.